Preheat oven to 190 degrees celsius and line a 12-hole muffin tin with muffin cases.
Place the bananas into the Thermomix bowl and mix on Speed 6, 5 seconds. Scrape down the sides of the bowl and repeat once more.
Add the greek yoghurt, honey, vanilla extract, melted coconut oil and egg and mix on Speed 4, 15 seconds, or until well combined.
Add the plain flour, bi-carb soda, cocoa powder and salt and mix on Speed 4, 5 seconds. Scrape down the sides of the bowl and repeat for a further 2-3 seconds or until just combined (don't over-mix the ingredients).
Fold through half of the chocolate chips with the spatula.
Divide the mixture between the muffin cases (filling to ⅔ of the way). Sprinkle with the remaining chocolate chips.
Bake for 15 minutes or until cooked through.Allow to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.